Non-equilibrium nuclear spin distribution function in quantum dots subject to periodic pulses

TL;DR

This paper develops a semi-classical model to analyze how periodic laser pulses influence electron spin coherence in quantum dots, revealing resonance conditions and non-equilibrium nuclear spin distributions.

Contribution

It introduces an analytical approach using Floquet theory to predict resonance peaks and describes the non-equilibrium nuclear spin distribution under periodic pulsing.

Findings

Resonance conditions accurately predict peak locations in Overhauser field distribution.

Periodic pulsing induces a non-equilibrium nuclear spin distribution.

Hyperfine coupling distribution affects electron spin dynamics.

Abstract

Electron spin dephasing in a singly charged semiconductor quantum dot can partially be suppressed by periodic laser pulsing. We propose a semi-classical approach describing the decoherence of the electron spin polarization governed by the hyperfine interaction with the nuclear spins as well as the probabilistic nature of the photon absorption. We use the steady-state Floquet condition to analytically derive two subclasses of resonance conditions excellently predicting the peak locations in the part of the Overhauser field distribution which is projected in the direction of the external magnetic field. As a consequence of the periodic pulsing, a non-equilibrium distribution develops as a function of time. The numerical simulation of the coupled dynamics reveals the influence of the hyperfine coupling constant distribution onto the evolution of the electron spin polarisation before the next laser pulse. Experimental indications are provided for both subclasses of resonance conditions.